A. Scott Berg didn't enroll at Princeton until almost 100 years after Woodrow Wilson did. But by now, Berg is well acquainted with the man who led the nation into World War I and promoted (but couldn't get the U.S. to join) a League of Nations to help end all wars. "Wilson" is the Pulitzer Prize-winning biographer's most ambitious book. From his Hollywood Hills home, Berg (holding a tiger-handled umbrella in honor of the Princeton mascot) is a one-man band of research and writing, and never more intensely than in unveiling the game-changing 28th president of the United States.

We live very much in a world Woodrow Wilson created. I believe all our foreign policy goes back to a single sentence in a single speech he gave on April 2, 1917, that the world must be made "safe for democracy." The bulk of our economic policy is based on the federal reserve system, which Wilson introduced.

The friction between the executive and legislative branches today is the most intense since the days when the Democratic Woodrow Wilson encountered an increasingly hostile and Republican Congress.

The big difference between Obama and Wilson is that Wilson maintained a constant dialogue with Congress, where I now find Obama often lurching from crisis to crisis. I think he was able to get more legislation passed and was better able to articulate why he wanted legislation passed.

He came to the White House with a short resume: President of Princeton and two years as governor of New Jersey.

No one had less "experience" than Woodrow Wilson. I suggest that it's the most meteoric rise in U.S. history, that a man came from virtual obscurity being a college president who'd written some books, and within two years he's president of the United States. He used to say he ran for public office to get out of academia. He said politics was child's play next to that.

We are so familiar with other major wartime presidents, like Lincoln, FDR. Why not Wilson?

He was an academician for most of his life and has been written about mostly by academicians. They are heartless, even soulless books. Wilson's views on race look so archaic as to be unbelievable, certainly intolerable, and that has worked against his reputation. And the photographs we have of him are severe and somewhat forbidding. Yet he had humor; he loved to sing and dance and tell jokes, and that's what's [been] missing. Women adored him, and he adored women.

Is World War I getting lost along with Wilson?

World War I was in many ways the first modern war, and in essence what FDR did is build on the machinery Wilson left for him. Wilson took an isolationist country with an army the size of Portugal's and within a year had mobilized 2 million soldiers in the greatest fighting machine the world had seen. In so doing he also created the ground floor of the military-industrial complex by joining big business with the military. As a result, the United States emerges from World War I as the first modern superpower.

Hard to believe, but as a teenager, you had a Wilson poster on your wall. What surprised you about him during your research?

The pathos of his life was more intense than I had imagined. Late in his administration, after his stroke, he sits in the East Room watching the documentary footage of his [triumphal 1919] arrival in Paris, and then he gets up and limps out of the room. It was just months earlier, and here was the "savior of the world" now just this completely broken man, physically, mentally, emotionally. I had never seen a book that humanized him, that gave me a sense of his personality. I found him to be more vivid in every respect than I had imagined. He was more of an idealist than I thought, but also more of a Southern racist , and more suppressive of dissent, going after [Socialist presidential candidate and pacifist Eugene V.] Debs the way he did.

Another thing that was revealed to me was his incredible obstinacy. When I started the book, I thought he was charmingly uncompromising, but in the end I realized he shot himself in the foot, or worse, he stabbed himself in the heart.

Did you find any brand new material?

Two caches emerged: When Wilson's last grandchild, National Cathedral Dean Francis Sayre, died, his family found trunks of letters belonging to his mother, Woodrow Wilson's daughter Jessie. There were thousands of letters — lots of intimate family drama. They were a gold mine.

Then the second cache was Dr. Grayson's [Cary T. Grayson was Wilson's aide and personal physician] last son's. The family found a trunk full of notes and letters to his fiancee who became his wife.

[One letter concerned] an assassination attempt, a madman in a Chicago hotel who wanted to stab Wilson. He leaped to his death. It wasn't in a newspaper; it was nowhere. Even Wilson sort of slept through it. Grayson said: "I write to you, darling, to say we almost had a tragedy!" And the other thing is the secret procedure where Wilson had [nasal] polyps removed but they didn't tell anybody. I thought this really was a dress rehearsal for [the stroke] that happened a year later: They knew how to keep medical secrets.

What happens when we are paperless and there are no more hidden letters and journals?

This is the biographer's nightmare. Do we collect people's tweets? It's the only record we're going to have. We won't have the breadth or the depth and we won't have those happy occasions when trunks of papers get discovered. Where is the record going to be?

[Wilson] was unusually articulate. He left no thought unexpressed. This is a man who wrote down everything he ever thought or felt.

There's already a film in the works based on your book. Could all the attention change the perception of Wilson?

I don't care whether you love him or hate him, but I'd at least like you to know about him: What he did with labor, the eight-hour workday, workers' compensation, appointing [Louis] Brandeis as the first Jew on the Supreme Court. Just the way he redefined how presidents can and should act.

How does "Wilson" differ from your earlier biographies? It took 13 years.

And I never had an uninteresting day! He never failed me as a character; he was such a good writer, and almost everything [about him] had some reference to the world we live in today.

This was far more difficult, in large measure because once you get into a presidential archive, it's endless. What about the secretary of State's papers? The secretary of Agriculture's papers? Should you go through Clemenceau's, and maybe Lloyd George's? That part is difficult. A presidential life covers everything.

I believe a biographer's task is to paint the times as well as the life; it's my job to give the background, and there's no part of America's life or the world's life of that period that Wilson did not touch. The biographer's job is the same as the novelist's or the playwright's, to unfold drama tellingly, [not to be like] what Gore Vidal called "the scholar squirrels."

Is there a particular moment of his life where you would have liked to have been a fly on the wall?

After Wilson gives the speech to the joint session of Congress asking for a declaration of war, and everyone cheers and applauds, Wilson and Edith drive back to the White House in silence. Wilson goes into his office, puts his head down on the table and sobs. Wow. A president who not only realizes that he is about to send all those men to war but that he is going to be personally responsible for the deaths of many of them. [In] the speech he gives at the American cemetery in Paris on Memorial Day 1919, he actually says as much. That just rips me apart. I have not seen that said of any other president.

What do you make of the current vogue of hatred for Wilson by the likes of Glenn Beck?

Well, it's crazy. I believe he said Woodrow Wilson is the most evil man who ever lived, and Hitler was sixth on that list. That Woodrow Wilson, this minister's son who loved peace and freedom, is Satan is just astounding to me. Is having a graduated income tax because of Wilson the most evil thing that has ever happened?

At the end of World War I, Wilson was like a demigod in Europe. How did he handle celebrity?

I think he remained as modest as any Presbyterian minister's son could remain. It's impossible to ignore the adulation, but I don't think he ever fully believed it. He definitely felt he was on a mission and felt appointed to carry out that mission. That moment after he gets elected and [his] campaign manager comes to him for a job, and he says, "You have nothing to do with this — this was all Providence, this was all foreordained."

His League of Nations [national barnstorming] tour was for a cause. He was not campaigning for himself; he was campaigning for an idea, or an ideal. I don't think of Wilson as messianic, but he was definitely a martyr. He truly did feel he owed it to those who gave their lives. I'm inclined to think Wilson is the most passionate man who ever inhabited the White House.